During various stages in the manufacturing of integrated circuits, the integrated circuits need to be tested to verify the quality. The testing of the integrated circuits may be performed by using probe cards to probe the contact pads or metal bumps on the surfaces of wafers or chips.
The pitches of the contact pads become increasingly smaller. For example, peripheral pads that are formed at the peripherals of chips have reached as small as about 40 μm. For pad arrays, the pitches also reached as small as about 130 μm. The 40 μm pitch of the contact pads also requires the pitch of the probe pins in the corresponding probe card to be 40 μm. This posts a problem for assembling the probe heads having the small pitch probe pins.
In a conventional probe head assembling process, holes are first drilled in a upper guide plate and a lower guide plate. Probe pins are inserted into the holes in the lower guide plate, and then inserted into a film, which is used for fixing the spacing between the probe pins. After all probe pins are inserted into the film, the probe pins are inserted into the holes in the upper guide plate. Each of the probe pins may have a middle portion, which is located between the portion of the probe pin that is inserted into the upper guide plate and the portion of the probe pin that is inserted into the lower guide plate. The middle portion may have a slightly flattened shape.
There are various issues observed in the formation of the conventional probe heads. For example, the insertion of the probe pins into the upper and lower guide plates were often handled manually. When handling very thin probe pins, for example, with diameters ranging from 1 mil to 4 mils, the probe pins are prone to damage easily. In addition, it is difficult to drill holes in the upper and lower guide plates having pitches as small as about 40 μm. The upper and lower guide plates may be damaged by the drilling process. Particularly, when drilling the holes in the upper guide plates, the material between the holes may be ripped apart. Accordingly, when the pitches of the probe pins are reduced to close to 40 μm, the assembly of the respective probe heads has a low manufacturing yield.